With a greater appreciation as to environmental damage associated with pesticide usage, there are ever-increasing limitations as to the classes of chemical compounds suitable as pesticides, as well as limitations when those pesticides can be spread on a crop. In many cases, in order to ameliorate environmental damage associated with pesticide application, pesticide use is mandated during seasons when the pest lifecycle is at the most vulnerable stage to limit dosing and collateral ecological toxicity. As integrated pest management has been endorsed by environmental regulatory agencies, industry associations and entomologists, more judicious pesticide usage should be expected in the future.
An ongoing problem in minimizing pesticide usage is the difficulty in delivery of a pesticide efficiently to a target plant within a large area of cultivated vegetation. A practical labor-saving approach to pesticide delivery to such as golf courses, parks, lawns, gardens and agricultural fields has been broadcast application of granular products containing a pesticide with equipment such as a rotary spreader. Using granular products having particle sizes in the range of about 1 millimeter to about 10 millimeters, an operator can cover a large area with minimal distance traversed by the spreader itself while at the same time applying the granular active agent with relative uniformity over the desired area. Unfortunately, such granular active agents often remain in solid or semisolid form for a considerable time following application. Since the pesticide is typically physically bound within the granule, the active agent efficacy is reduced or delayed, potentially resulting in a loss of product activity via volatilization or photodegradation with the consequence of lower efficacy and higher cost.
A further consequence of granular active agent distribution is that the granules are subject to removal by plant culture operations such as mowing or aerating, or environmental factors such as wind and rain, especially on sloping ground where the underlying soils have low percolation rates, where ground cover is sparse or areas of high foot traffic. The ability to adjust material density to respond to high wind dispersion areas and other such environmental factors has met with limited success as no single material has all the desired properties of formulation densities over a range with regard to cost, processability, transport stability, and dust formation.
A material that has a high density of active agent per unit mass of granular material tends to be spread with an excess of active agent used per unit area of ground, while low density material tends to be underutilized per unit area of ground. As most vegetation culture granular products are sold by total weight instead of active agent density per unit mass, the ability to adjust product density is important in packaging operations.
The inability to control uniformity in active agent application and therefore efficacy is altered due to excessive concentration of the product within certain treated areas while other areas suffer diminished active agent concentrations. Additionally, a long-persistent granule creates a greater likelihood that people and beneficial insects and other animals will come into physical contact with the granules, resulting in undue human health effects and environmental degradation. An alternative to long-persistent granule products is spray application of a liquid active agent. Unfortunately, spray treatments require considerable skill for application and result only in contact to exposed foliage with other surfaces receiving only indirect drainage from exposed foliage. Additionally, spray treatment tends to dissipate quickly. Due to spray atomization of liquid active agents, a considerable amount of active agent is lost through volatilization and wind drift thereby requiring greater quantities to reach pests dwelling on the underside of foliage. The net result is inefficient pesticide usage; non-target hazard effects to people, wildlife, and non-target property; as well as other deleterious effects of pesticides, such as leaching into the soil through rain contact causing environmental wastewater management issues.
Thus, there exists a need for a plant culture delivery medium for carrying of active substance amenable to the density modification.